1. Field of the Invention
The present invention relates to audio data processing, and more particularly, to a method and apparatus for converting audio data compressed in a predetermined format into audio data compressed in another format.
2. Description of the Related Art
MPEG-2 layer 3 or MPEG-1 layer 3 (also known as MP3) audio devices are being gradually replaced by MPEG-4 devices with high compression efficiency. MPEG-4 is being adopted by many digital service operators such as the European digital audio broadcasting (DAB) system, in order to process video and audio signals. In particular, a bit sliced arithmetic coding (BSAC) format rather than an advanced audio coding (AAC) format is used in audio signal processing. On the other hand, an AACPlus format that combines a spectral band replication (SBR) technology with an AAC format is also used as an audio signal processing technology in satellite digital multimedia broadcasting.
Further, contents including audio data compressed in an AAC format or a BSAC format have been widely used in the audio multimedia market. With this in mind, it is very important to provide multimedia services continuously to suit a user's taste or environment. In particular, since a plurality of devices are incorporated in a user's computing environment and various content formats are used worldwide, demands for multimedia services that suit a user's taste or environment have been further increased. Here, an environment can mean a network or content formats which a user uses. Multimedia kernel technologies for providing services suitable for a variety of environments to the user include scalability and conversion methods. In the scalability method, data is made to be suitable for a variety of environments. In the conversion method, audio data compressed in one format is converted into audio data to be compressed in another format.
In general, in the conversion method, audio input data compressed in a predetermined format is fully decoded to generate pulse coding modulation (PCM) data, and the PCM data is then fully coded in a desired compression format. Accordingly, a decoding unit is conventionally needed to fully decode audio input data, and a separate coding unit is needed to fully code data in a desired format. Accordingly, the conversion method is expensive and time-consuming.